Drive for an adjuster device in a motor vehicle

ABSTRACT

A drive for an adjuster device in a motor vehicle. The drive includes a drive motor, a drive element mounted to rotate about a drive axis, and a self-locking device for the drive element, which, when the drive motor is not energized, locks the drive element with the locking element. The locking element may be brought out of engagement with the drive element in the radial direction relative to the drive axis on energizing the drive motor.

BACKGROUND

The invention relates to a drive for an adjuster device in a motorvehicle.

A drive of this kind comprises a drive motor, a drive element mountedrotatable about a drive axis, e.g. in the form of a rotor of the drivemotor; as well as a device for the self-locking of the drive elementwhich in the de-energized state of the drive motor locks the driveelement with a locking element.

From DE 199 42 362 C1 a self-locking electric drive is known having anelectric motor and a transmission on the output side with a transmissionhousing, a gear output shaft rotatable relative to the transmissionhousing, and a drive for the self-locking of the gear output shaft. Theself-locking electric drive has a locking element which at the same timeas the electric motor is operated is displaceable electrically from afirst position to a second position, as well as an element which isfixed relative to the transmission housing wherein the locking elementin the first position produces a positive coupling between the gearoutput shaft and the fixed element and wherein this coupling isdisengaged in the second position. The fixed element is thereby formedby a gear axis on which the locking element is displaceably mounted inthe axial direction. With this arrangement, a self-locking electricdrive can be produced in which a sufficiently strong self-locking actionis ensured. Thus, with the electric motor switched off, torque appliedon the output side is prevented from being transferred to the driveside, without the efficiency of the drive hereby being adverselyaffected too much. However, this arrangement has the drawback in thatthe ability of the locking element to move in the axial direction toproduce and clear the self-locking action requires a certain extensionin the axial direction. This is undesirable, particularly in the case offlat motors of electric driver for motor vehicles, where due to spacelimitations, obtaining the smallest possible extension of a motor in theaxial direction is of great importance.

From WO 94 23220 A a drive is known consisting of a drive motor, a driveelement mounted rotatable about a drive axis and a device for theself-locking of the drive element. In the de-energized state of thedrive motor the drive element is locked with a locking element. Thelocking element can be brought out of engagement with the drive elementin the radial direction relative to the drive axis for operating thedrive motor.

In DE 199 43 692 A1 a disc rotor motor is described, more particularlyfor adjuster devices in motor vehicles. No device is given for the selflocking of the drive element.

From FR 2 405 586 A a rotating electro-mechanical drive is known inwhich in the de-energized state of the drive motor a locking element isfixed through magnetic forces of a permanent magnet.

SUMMARY

An object of the invention is therefore to provide the simplest possibleself-locking design of a motorized drive for an adjuster device.

The locking element for operating the drive motor can be brought out ofengagement with the drive element in the radial direction relative tothe drive axis in order to permit movement of the drive element duringenergizing of the associated drive motor. The locking element is in thede-energized state of the drive motor fixed by magnetic forces which aregenerated by the stator of the drive motor in a position which locks thedrive element.

Bringing the locking element out of engagement can, on the one hand takeplace when energizing the drive motor, e.g. by using the electriccurrent, which is used to energize the drive motor at the same time toactuate the locking element, possibly by means of an electromagnet. Onthe other hand, it can also be provided that the locking of the driveelement is cleared prior to energizing the motor so that at the start ofoperating the motor the locking element is in each case out ofengagement with the drive element. This type of timed control of liftingthe locking element from the drive element can be particularlyadvantageous if the locking element is in positive engagement with thedrive element.

Conversely, the locking element on switching off the drive can be movedradially into engagement again with the drive element so that arotational movement of the drive element about its drive axis is lockedand the transfer of forces applied on the output side to the drive sideis prevented (self-locking). This engagement process can be controlledso that there is no sudden engagement but a controlled measuredengagement, e.g., to prevent noises.

The solution according to the invention has the advantage that itenables a self locking action which, on the one hand, does not impairthe efficiency of the drive and which, on the other hand, requires nospecial extension of the drive motor in the axial direction.

The solution according to the invention is therefore particularlysuitable for use in the case of flat motors which have for example arotor in the form of a disc rotor wherein the locking element duringenergizing of the flat motor is lifted in the radial direction from thedrive element so that the forces generated by the flat motor lead to arotational movement of the drive element. When using the solutionaccording to the invention for a flat motor having a disc rotor (discrotor motor) in which the locking element can be brought in and out ofengagement radially with the rotor (armature disc), it enables the largefriction radius of the armature disc to guarantee a sufficientself-locking action with comparatively small braking forces. Thepermanent magnetic energy which is constantly available locks thearmature disc when the motor is not energized, that is on applying aforce on the output side, e.g. on a window pane which is to be adjustedthrough the drive or on a seat part which is to be adjusted through thedrive. The self-locking action is hereby not generated in the firstinstance through the gear configuration but is obtained through apermanent magnetic brake which manages without any additional energysource.

In order to bring the locking element out of engagement with the driveelement when the drive motor is energized, according to a variation ofthe invention, an elastic element can be used which is coupled to thedrive motor in the suitable way so that during energizing of the drivemotor the locking of the drive element can be lifted.

In a particularly preferred variation of the invention the lockingelement can be brought electrically out of engagement with the driveelement.

In one variation of the invention the magnetic forces can be generatedfor example through a permanent magnet which forms the stator of thedrive motor.

Thus, a permanent magnet which is in any case provided as a stator inthe motor can hereby be used to generate the brake force with which thedrive element is locked when the (de-energized) drive motor is switchedoff.

The locking element has itself a first magnetizable section whosemagnetization fixes the locking element in a position in which it locksthe drive element. The said first magnetic section defines a firstmagnetic path for the magnetic flux which is generated by the magnetused to fix the locking element and with which a magnetic force isproduced which fixes the locking element in its position locking thedrive element.

In order to bring the locking element out of engagement with the driveelement when the drive motor is energized it is possible to use anelectromagnet which is for example energized together with the drivemotor and which generates a magnetic field through whose flux or forceaction the locking element is brought out of engagement with the driveelement. Through a suitable timed control of the energizing of theelectromagnetic or the lifting of the current through the electromagnetit is thereby possible to control the timed connection between the startof operation of the drive motor and the release of the locking element,as well as to obtain a smooth re-engagement of the locking element inthe drive element when the drive motor is switched off.

According to one embodiment of the invention the field produced by theelectromagnet deflects the magnetic flux serving to fix the lockingelement when the drive motor is de-energized so that the resultingmagnetic flux brings the locking element out of engagement with thedrive element. With the deflection of the magnetic field the (permanentmagnetic) flux which fixes the locking element when the drive motor isde-energized is, after the motor and electromagnet are energized, nolonger guided over the short circuit acting as the friction brake but aside path is offered for the flux in which this causes no fixing of thelocking element in a position in which it engages with the driveelement. The friction brake is thereby released and the drive elementcan rotate freely. When the motor is switched off the (permanentmagnetic) flux is again guided through the short-circuit acting as thebrake and thus re-establishes the self-locking action.

According to another embodiment of the invention the (permanentmagnetic) flux fixing the locking element when the drive motor isde-energized is displaced through the magnetic field which is producedby means of an electromagnet when the motor is energized so that theresulting magnetic flux brings the locking element out of engagementwith the drive element. During the displacement of the magnetic fieldthe (permanent magnetic) flux is thus displaced by a counter excitationwhich is produced by energizing an electromagnet. Energizing theelectromagnet takes place at the same time as the motor is switched onand leads to a displacement of the (permanent magnetic) flux into a sidepath provided for this. When the motor is switched off again thecounter-excitation is automatically deactivated and the locking elementis fixed again by the magnetic flux in a position in which it locks thedrive element.

According to a further variation of the invention a permanent magnetthrough which the locking element can be fixed in a position locking thedrive element, as well as an electromagnet or the magnetic fieldsproduced by these two magnets, are integrated into one hybrid magneticcircuit so that the permanent magnetic flux superimposes theelectromagnetic flux and the locking element can hereby occupy twostable positions (end positions) of which one engenders the locking ofthe drive element and the other enables a rotational movement of thedrive element. In both stable positions (end positions) theelectromagnet can hereby be de-energized each time whereby thetransition from one stable position to the other is triggered through atemporary energizing of the electromagnet with a current impulse. As aresult with the embodiment of the invention described above a permanentmagnet which is provided in any case in the drive and serves to producethe stator field can be directed into a hybrid magnetic circuit so thatits flux is superimposed on the electromagnetic flux produced by anelectromagnet and the release and closing of the brake is brought abouteach time through a short current impulse when switching the motor onand off whereby the two end positions of the locking elementcorresponding with the associated stable positions of the brake are eachtime occupied de-energized.

A magnetic brake unit of this kind is owing to the permanent magneticpre-magnetization characterized through small electrical and mechanicaltime constants, that is the current and the brake force rise up rapidly.The brake force can be introduced in a controlled measured manner bysuitably adjusting the current which is used to energize theelectromagnet. In particular the brake unit can be intelligentlycontrolled through the motor electronics, e.g., if a vertically movablewindow starts to become jammed the motor brakes faster than when thewindow pane moves orderly into an end position. The hybrids to be usedfor producing a hybrid magnetic circuit furthermore have the advantagethat they are small and light.

In a further development of the invention the locking element has abrake element which in order to lock the drive element acts on same,namely preferably as a (elastically designed) friction element. Thelocking element or its brake element is for this guided movable in theradial direction on a guide device, namely is more particularly radiallydisplaceable. It is however possible to provide a positive engagement ofthe locking element in the drive element instead of a force locking orfriction locking engagement.

Furthermore in order to intensify the brake force (in the case of aforce locking brake action) or to deliberately adjust (e.g. lengthen)the path required for the locking element to move in and out(particularly in the case of a positive locking brake action) thelocking element can be actuated through a lever mechanism.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features and advantages of the invention will now be apparentfrom the following description of an embodiment with reference to thedrawings.

FIG. 1 is a diagrammatic view of a drive motor for an adjuster device ina motor vehicle, with a device for locking the rotor in the de-energizedstate;

FIG. 2 is a drive motor according to FIG. 1 at the start of energizingthe motor;

FIG. 3 is a drive motor according to FIG. 1 during operation of themotor.

DETAILED DESCRIPTION

FIG. 1 shows of a drive motor designed as a flat motor for an adjusterdevice in motor vehicles, e.g. for adjusting a window pane, (electricwindow lifter) or for adjusting a seat part (electric seat adjuster) adisc rotor 1 (armature disc) as well as a stator 2 which is formed bypermanent magnets 21, 22. The disc rotor 1 is mounted to rotate about anaxis A on a shaft (not shown in FIG. 1).

The drive motor illustrated in FIG. 1 is a result of the design of therotor 1 characterized as a disc rotor or armature disc in particularthrough its small extension along the drive axis A of the disc rotor 1.This plays a significant part in adjuster devices in motor vehicles,e.g., in the form of an electric window lifter or electric seat adjustersince often there is only a little space available for the drive motor.

When the drive is switched off, i.e. de-energized in order to prevent aforce applied on the output side, e.g., on a window pane to be adjustedor on a seat part to be adjusted from being transferred to the driveside, the drive motor is allocated a brake device 3, 4, 5 whichcomprises a locking element 3, a guide device 4 for guiding the lockingelement 3 in the radial direction R relative to the drive axis A and anelectromagnet 5 for actuating the locking element 3.

The locking element 3 comprises an elastically deformable brake element30 in the form of a friction brake which can be brought into engagementwith the outer edges of the disc rotor 1 and thereby locks the discrotor 1 so that it cannot rotate about the drive axis A. The brakeelement 30 is connected to a body of magnetic material which comprises afirst magnetizable section with a current path 31 as well as a secondmagnetizable section with a current path 32 which can each form a pathfor the magnetic flux which is generated by the stator 2 orelectromagnet 5. Furthermore the locking element 3 comprises guideregions 35 which are guided together with the two current paths 31, 32displaceable in a radial direction R on a guide element 4 consisting oftwo elongated guide parts 41, 42. A magnetic plate 40 is mounted on theguide device 4 on the side remote from the disc rotor 1 and stator 2.

The electromagnet 5 is connected to the locking element 3 so that it canbe displaced together with same in the radial direction R relative tothe drive axis A.

FIG. 1 shows the electric drive motor 1, 2 when it is switched off, i.e.in the de-energized state. In this case the electromagnet 5 is alsode-energized. The magnetic flux F is therefore solely generated by thepermanent magnets 21, 22 of the stator 2. The magnetic flux F extendsthrough the shortest available path, namely the first path 31 of thelocking element 3. A magnetic force is hereby generated which moves thebrake element 30 in the direction of the drive motor 1, 2 so that theelastically deformable brake element 30 presses against the outer edgeof the disc rotor 1 and locks it through friction action. The disc rotor1 can therefore not turn about its drive axis A and the transfer oftorque applied on the output side to the drive side is ruled out. Thiscorresponds to a self locking action of the drive motor 1, 2 in thede-energized state. The operating air gap L between the outer edge ofthe drive motor 1, 2 and the locking element 3 is hereby minimized.

FIG. 2 shows the drive motor 1, 2 of FIG. 1 when the drive motor isswitched on, i.e., at the start of energizing of the drive motor 1, 2whereby at the same time the electromagnet 5 is energized. The currentdirection of the current flowing through the electromagnet 5 is therebyselected so that the magnetic flux generated by the electromagnet 5 runsoppositely to the magnetic flux generated by the permanent magnet 21, 22and thus displaces same (magnetic field displacement). In the region ofthe operating air gap L between the outer edge of the drive motor 1, 2and the locking element 3, the permanent magnet 21, 22 on the one sideand the first magnetic section 31 of the locking element 3 facing theouter edge of the drive motor 1, 2 on the other are oppositelymagnetized so that the brake element 3 is repelled in the radialdirection R and the operating air gap L is enlarged. The brake whichensures the self-locking action in the de-energized state of the drivemotor 1, 2 is thereby released.

In the situation shown in FIG. 3 the brake is completely opened. Theresulting magnetic flux F generated by the permanent magnet 21, 22 andthe electromagnet 5 now extends through a side path which is formed bythe second magnetic section 32 of the locking element 3 and by theplate-shaped section 40 of the guide device 4. The locking element 3 ishereby fixed in a radial position in which the brake element 30 islocated out of engagement with the disc rotor 1 so that this can rotatefreely about the drive axis A and a torque applied on the drive side canbe transferred to the output side.

Very similar conditions to those described above regarding the magneticfield displacement exist with the so-called magnetic field deflection.Here, a switch (magnetic switch) is electrically actuated and themagnetic field is hereby deflected through a second flux path.

Furthermore, the arrangement according to FIGS. 1 to 3 also meets therequirements for a construction with hybrid magnets with two stable endpositions which can be occupied in the de-energized state. Theactivation and deactivation of the brake takes place for example througha short current impulse according to the flip-flop principle.

The brake device 3, 4, 5 illustrated in FIGS. 1 to 3 for a disc rotormotor 1, 2 has the advantage that it causes in the de-energized state areliable self-locking of the drive without influencing the efficiency inthe operation of the motor and also does not influence the extensioni ofthe flat motor 1, 2 in the axial direction, thus along the drive axis A.

1. Drive for an adjuster device in a motor vehicle, comprising: a drivemotor (1, 2) with a stator; a drive element mounted rotatable about adrive axis; and a device for self-locking of the drive element which ina de-energized state of the drive motor locks the drive element with alocking element, wherein the locking element for operating the drivemotor is brought out of engagement with the drive element in a radialdirection relative to a drive axis and wherein the locking element inthe de-energized state of the drive motor is fixed by magnetic forceswhich are generated through the stator of the drive motor in a positionwhich locks the drive element.
 2. The drive according to claim 1 whereinthe locking element is lifted in the radial direction from the driveelement.
 3. The drive according to claim 1 or 2 wherein the driveelement is formed by a rotor of the drive motor.
 4. The drive accordingto claim 3 wherein the drive element is a disc rotor.
 5. The driveaccording to claim 1 wherein the locking element is brought out ofengagement with the drive element by an elastic element.
 6. The driveaccording to claim 1 wherein the locking element is electrically broughtout of engagement with the drive element.
 7. The drive according toclaim 1 wherein the magnetic forces are generated by a permanent magnet.8. The drive according to claim 1 wherein the locking element has afirst magnetic section.
 9. The drive according to claim 8 whereinthrough magnetizing the first magnetic section the locking element isfixed in a position which locks the drive element.
 10. The driveaccording to claim 9 wherein the first magnetic section defines a firstmagnetic path for magnetic flux.
 11. The drive according to claim 1 or 8wherein in the first magnetic section runs a magnetic flux through whichthe locking element is fixed in a position locking the drive element.12. The drive according to claim 1 wherein the locking element isbrought out of engagement with the drive element by energizing anelectromagnet.
 13. The drive according to claim 12 wherein theelectromagnet is energized at the same time as the drive motor.
 14. Thedrive according to claim 11 wherein the electromagnet generates amagnetic field through which the locking element is brought out ofengagement with the drive element.
 15. The drive according to claim 11wherein the magnetic field generated through the electromagnet divertsthe magnetic flux so that the resulting magnetic flux brings the lockingelement out of engagement with the drive element.
 16. The driveaccording to claim 11 wherein the magnetic field generated by theelectromagnet displaces the magnetic flux so that the resulting magneticflux brings the locking element out of engagement with the driveelement.
 17. The drive according to claim 14 wherein the resultingmagnetic flux runs in a side path of a second magnetic section of thelocking element.
 18. The drive according to claim 7 or claim 12 whereinthe permanent magnet and the electromagnet are integrated in a hybridmagnetic circuit so that the permanent magnetic flux superimposes theelectromagnetic flux and the locking element thereby occupy two stablepositions wherein in the one stable position the drive element is lockedby the locking element and in the other stable position the lockingelement is out of engagement with the drive element.
 19. The driveaccording to claim 18 wherein the electromagnet is each timede-energized in both stable positions of the locking element.
 20. Thedrive according to claim 18 wherein the transition from one stableposition into the other stable position is triggered by energizing theelectromagnet with a current impulse.
 21. The drive according to claim 1wherein the locking element has a brake element which in order to lockthe drive element acts on the drive element.
 22. The drive according toclaim 21 wherein the brake element acts with friction on the driveelement.
 23. The drive according to claim 1 wherein the locking elementis movably guided in the radial direction on a guide device.
 24. Thedrive according to claim 1 wherein the locking element is displaceablein the radial direction.